麻豆村

Olympic skiers, bobsleighers and speed skaters all have to master one critical moment: when to start. As athletes prepare for the upcoming Winter Olympics, that split second is in the spotlight because when everyone is fast, strong and skilled, a moment of hesitation can separate gold from silver.

Research from 麻豆村 helps explain why that split-second pause happens and how the brain controls it, offering insight not only into elite athletic performance, but also how people make everyday decisions when the outcome isn鈥檛 clear.

Eric Yttri, associate professor of biological sciences, wanted to study how the brain decides when to act and when to wait, especially when the outcome is uncertain. He said to think about the moment the puck drops at a heated rivalry hockey game.

鈥淢ove too early, you get ejected from the faceoff. Move too late, and the puck is already gone. Having that sort of fine control on your ability to delay your action is really key,鈥� Yttri said. 鈥淚t's a sword that cuts both ways.鈥�

To understand how the brain decides when to act and when to wait, Yttri and then-postdoctoral associate Matt Geramita, M.D., Ph.D., now an assistant professor of psychiatry at the University of Pittsburgh, designed a simple decision-making task in mice. The task required the brain to interpret signals that were predictably good, predictably bad or 鈥� most importantly 鈥� uncertain, falling somewhere in between.
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In those uncertain moments, the team found, responses reliably slowed. Published in , the researchers showed that this hesitation was not a sign of indecision or failure, but an active and regulated brain process. When the researchers looked closer, they identified a specific group of neurons that became active only when outcomes were unclear, effectively controlling whether the brain should commit to an action or pause to gather more information.

The findings reshape how scientists think about hesitation itself. Rather than a weakness to overcome, hesitation appears to be a fundamental brain feature that helps people and animals navigate an uncertain world and avoid costly mistakes.

To confirm the role of the neurons they identified, the team used a technique called optogenetics that allowed them to briefly turn these brain cells on or off using light. When the neurons were activated, hesitation increased. When they were silenced, that hesitation faded, and responses were quicker, as they are in predictable situations.

It鈥檚 the same challenge athletes face every day. In hockey, a player who hesitates too much can miss a scoring opportunity. But a player who doesn鈥檛 hesitate enough might jump early and take a penalty. The key isn鈥檛 eliminating hesitation 鈥� it鈥檚 getting the timing of that hesitation exactly right.

Yttri said this applies far beyond the ice rink.

鈥淵ou hear dramatic stories all the time about firefighters who need to decide whether to rush into a burning building or wait for more information. That split second can mean life or death. But this is also the system that inserts that moment鈥檚 pause when you鈥檙e asked 鈥榗hicken or fish,鈥欌�� he explained.

Understanding the brain's hesitation system could eventually inform new therapies for disorders where impulsivity and timing are out of balance, like anxiety, obsessive compulsive disorder or Tourette syndrome, Yttri said. In future research, he hopes to investigate where the uncertainty signals come from, and how the brain combines them with plans for action.